The present invention relates generally to apparatus for applying foamed treating liquor across the width of a traveling substrate such as textile fabric or the like.
The finishing of textile fabrics or like substrates typically includes the application of dye or other treating liquor. In the past, various methods and apparatus employed for this purpose provided for the passage of the traveling dry fabric or substrate through an immersion bath of the treating liquor, by which the fabric took on a significant amount of the treating liquor. The excess liquor absorbed or adsorbed by the fabric, of course, required removal, usually through heat-induced drying of the fabric or substrate.
With the significant increases of energy costs over recent years, there has arisen an increasing concern for reducing the energy costs associated with textile finishing operations. As one means of accomplishing this objective, various methods of applying treating liquor to fabric have been proposed as alternatives to the immersion methods so as to minimize the necessity and resultant energy costs associated with drying of wet treated fabrics. One particularly successful and now widely used alternative technique involves the application of the treating liquor in a foamed condition so that the amount of so-called "wet pick-up" by the fabric being treated is maintained relatively low and, in turn, a minimal amount of fabric drying is required to remove the correspondingly low amount of excess treating liquor.
Present conventional apparatus for applying foamed treating liquor utilize a distribution chamber to distribute transversely the foamed treating liquor received from an input tube or similar conduit and to deliver the distributed foam to an elongate nozzle which extends transversely across the width of the traveling fabric or substrate to dispense thereon the foamed liquor. Effective prior apparatus for this purpose are disclosed in U.S. Pat. Nos. 4,237,818 and 4,402,200, commonly owned with the present invention. Specifically, U.S. Pat. No. 4,237,818 discloses an upstanding distribution chamber which flares transversely from a central collection section as the chamber extends vertically to apply the foamed treating liquor to the bottom surface of a traveling substrate. U.S. Pat. No. 4,402,200 discloses a flared distribution chamber circumferentially mounted on a cylindrical supporting member to achieve the desired transverse foam distribution while applying foamed liquor from above the substrate.
In each such prior applicator, the flared nature of the distribution chamber necessarily causes the foamed treating liquor to travel a greater distance from the inlet tube to the transverse ends of the nozzle than to the central area of the nozzle. It is recognized in the relevant art that foamed treating liquor degenerates quickly from its foamed state into its previous liquid state. Accordingly, these flared distribution chambers cause the foam emitted from the nozzles to be in varying states of foam degeneration along the length of the nozzle which can produce undesired side-to-side variations in the wet pick-up by the substrate or fabric of the liquor and, in turn, in the treating effect and appearance of the substrate. This problem is especially acute with distribution chambers having considerable height and width as may be required for substrates of substantial widths.